Piston-head.



PATENTED MAR. 3, mos.

A. J. ROBERTSON.

. I PISTON HEAD.

ILBD APR. 2. 1902 llnrrnn rates ATET T FFICE.

AROHIBALD .I. ROBERTSON,OF CHICAGO, ILLINOIS.

PlSTON-HEAD.

SPECIFICATIOM'fOrming part of Letters Patent No. 722,146, dated March 3,1903. Application filed April 2, 1902- Serial No. 101,092. 7 (N0 model.)

In all whom/ it 'ITI/(LZ/ concern:

Be it known that I, ARCHIBALD J. ROBERT- SON, a subject of the King ofGreat Britain, and a resident of Chicago, in the county of Cook andState of Illinois, have invented certain new and useful Improvements inPiston- Heads, of which the following is a specification.

This invention relates to pistons in reciprocating engines; and theobject is in general to provide an elastic or resilient connectionbetween the piston -rod and pistonhead, whereby to relieve working partsof the engine from sudden, violent, and ususual strains.

A further object of my invention is the construction of an elastic orresilient piston in which is stored at least a small portion of theenergy developed by the first impact of the motive agent to retain amore nearly uniform driving pressure throughout the whole stroke orcycle.

My device is particularly adapted for use in reciprocating engines formotor-vehicles, where the various working parts are necessarily small insize and light in Weight and where unusual or excessive strains arelikely to be produced in starting and stopping.

Where a rigid piston-head is employed, theimpact of the motive agent isagainst unyielding parts, and the pressure must be sufticient to startthe vehicle before the pistonhead will start to move. A piston embodyingmy invention will afford means for exerting a more gradually acceleratedpressure against the piston-rod and its connections, thereby avoidingsudden and unusual strains.

My invention consists generally in a double piston-head, the piston-headproper, which receives the impact of the steam or other motive agent,itself constituting a smaller cylinder, within the chamber of which,rigidly attached to the piston-rod, a subordinate or secondary head ordisk is capable of a limited reciprocating motion and myinventionfurther consists in the employment within the piston-head chamber ofconnecting means between the primary and secondary heads to giveelasticity or resiliency to their relative movement; and my inventionfurther consists in the various details of construction and incombinations of parts, all as hereinafrigidly bolted together.

ter described, and particularly pointed out in the claims.

My invention will be more readily understood by reference to theaccompanying drawings, forming a part of this specification, and inwhich-- Figure l is a central vertical longitudinal section of acylinder and piston therein embodying my invention. Fig. 2 is aperspective view of the preferred form of coil-spring employed toprovide the desired resiliency.

Referring now to the drawings in detail, I have shown a cylinder A and apiston-rod B of common or usual pattern and construction. Thepiston-head proper to facilitate manufacture with an interior chamberand to provide for the placing and adjustment of the parts thereinpreferably comprises the two similar and separable cup-shaped disks D D,Into the cylindrical chamber formed by these disks extends thepiston-rod B, carrying at its extremity, rigidly and suitably attachedthereto, the subordinate or secondary disk or head 0, preferablyoccupying the entire vertical sectional area of said chamber and capableof a limited reciprocating motion therein. The construction of this diskand chamber is analogous to the construction of the ordinary pistonheadand cylinder in all save that the proportions are necessarily differentand the movement of the disk much more limited. At each side of thesecondary disk or head I have shown a coil or spiral spring E ofsuitable size and weight, each being normally slightly and uniformlycompressed to retain said secondary disk substantially in the middie ofthe chamber. Movement of the disk with reference to the piston-headwithin the chamber of which it is located in either dimotion is thussubject to the resistance of one or the other of these springs. Thepistonhead proper is provided with the usual packing-rings F F, and Grepresents a packingring to prevent the entrance of steam into theinterior chamber, retained in place by means of the apertured nut 11.

It will be apparent that when the steam or other motive agent enters thecylinder at either side of the piston-head proper a slight motion willbe imparted to said head proper before power is communicated to theworking parts. In this manner not only will sudden and unusual strainsupon these parts be prevented, but when said head is driven in eitherdirection one or the other of said springs will be under greater (andits opposite less) than normal compression, resulting in at least asmall storage of energy, which is utilized to retain a more nearlyuniform driving pressure for a longer period of time during the strokeor cycle than would be possible when a rigid head was employed.

I do not desire to be limited to the use of spiral or other springs toprovide the desired resiliency. It is obvious that with proper air-tightconnections compressed air may be utilized to serve the same purpose andpossibly in an even more satisfactory manner. The essentially novelfeature of my invention is the employment of a double piston-head, theprimary being provided with a cylindrical chamber within which thesecondary is capable of an independent reciprocating motion, and meansfor giving resiliency to the relative movement between the two.

Having thus described my invention, I claim as new and desire to secureby Letters Patent 1. In a piston for reciprocating engines, thecombination, with a primary piston-head provided with an interiorchamber and a pistonrod extending into said chamber, of a secondary heador disk rigidly attached to said rod to reciprocate within said chamber,and means for giving elasticity to the relative movement of said primaryand secondary heads.

2. In a piston for reciprocating engines, the combination, with aprimary piston-head provided with an interior cylindrical chamber and apiston-rod extending into said chamber, of a secondary head or diskrigidly attached to said rod to reciprocate independently within saidchamber, and means Within said chamber for giving elasticity to therelative movement of said primary and secondary heads.

3. In a piston for reciprocating engines, the combination, with aprimary piston-head provided with an interior chamber and a pistonrodextending into said chamber, of a secondary head or disk rigidlyattached to said rod to reciprocate independently Within said chamber,and a suitable compression-spring at each side of said secondary head togive resiliency to the relative movement of said primary and secondaryheads.

AROHIBALD J. ROBERTSON.

Witnesses:

EVA B. J UDD, MARY F. LINCOLN.

